1$ Professor Leslie on Electrical Theories . 
to some intervening medium. But is it more difficult to con- 
ceive an effect produced at the distance of 1 000 miles, or at the 
1000th part of an inch ? Or have we ever any idea of the con- 
nexion between cause and effect, but that of constant concomi - 
tanzy ? To maintain, that no body can act where it is not, is, 
in fact, to assert, that the same body can be in two different 
places at the same time ; which is a contradiction of terms, and 
therefore completely absurd. 
And what advantage is gained by admitting an electric fluid ? 
All that can be demonstrated is the emission of light : and is 
not the difficulty increased by regarding, not the body itself, 
but a fluid residing in it, as the source ? Nor will the motion 
©f such a fluid in the least explain the phenomena ; on the con- 
trary, none of the effects that would necessarily result from its 
motion can be perceived. But, does not the profuse discharge of 
luminous matter from any substance constantly indicate a change 
of properties P And, would not an alteration, even though 
temporary, in the nature of an electric fluid, be inconsistent 
with the notions commonly received ? 
The various mechanical hypotheses which have amused the 
philosophic world, derive their origin from the early and inve- 
terate prejudice, that all motion is caused b y, impulse. Vortices 
and ether enjoyed but a temporary reputation ; and every so- 
ber inquirer was convinced, that such gratuitous assumptions, 
instead of simplifying the laws of nature, involved them in 
greater obscurity and perplexity. The question still recurred, 
what produced the motions of those elements ? The under- 
standing, bewildered and confounded amid the increasing diffi- 
culties, abandoned the pursuit : The imagination alone was de- 
lighted to dwell in mystery and illusive darkness. The chain 
of principles which direct this universe, terminates in the will 
of its Mighty Architect ; and prudence calls us to stop 
where the link appears the simplest, and not to strain beyond 
the limits of our faculties. Many speculations have been offer- 
ed on the subject of the magnetic fluid ; but, unfortunately, 
the properties gratuitously ascribed to it, beside their absolute 
insufficiency, are more complex than the facts which they are 
intended to explain. The hypothesis of an electric fluid is so 
